A prior art using such pumping sources includes certain essential items in common as to their functions mentioned below with a laser of the present invention.
These essential items in common are the following:
an elongate laser rod having a longitudinal axis defining radial and circumferential directions in transverse planes, the material of the rod being suitable for absorbing pumping light in order to amplify longitudinally propagating light to be amplified;
at least one pumping source for emitting a pumping beam of said pumping light from an emitting area whose small circumferential width requires said laser to form an angle of divergence in one of said transverse planes, at least initially; and 7 a reflector surrounding said rod while leaving at least one window to pass said pumping beam and constitute a light trap in which a fraction of said light that is not absorbed during a first passage through said rod is returned towards said rod for a subsequent pass.
One such prior laser is described in the article "Laser diode side pumping of neodymium laser rods," by F. Hanson and D. Haddock, published in Applied Optics, Vol. 27, No. 1, Jan. 1, 1988.
The reflector of this laser serves to increase the overall energy efficiency of the laser firstly by reducing losses of pumping light to the outside from the laser, and secondly by improving the uniformness of pumping, i.e. by making the power density of the pumping light more uniform in the volume of the laser rod, and more particularly across its cross-section.
Nevertheless, it remains desirable to further increase the efficiency of such a laser and also to make it more compact, i.e. to increase the ratio of the light power it is capable of delivering divided by its overall volume.
The present invention seeks in particular to avoid losses of pumping light to the outside from such a laser, to increase pumping uniformness, and also to provide a laser which is more compact.